This paper, which supplements that of Connorton (1985), shows how velocity components can be deduced from information about the groundwater head. Even though the groundwater head remains constant with depth, it is possible to estimate both the vertical and horizontal flow components from the groundwater-head distribution. The accuracy of these calculated flow components can be assessed by comparing with results obtained from solutions in terms of the groundwater potential which is a function of both horizontal and vertical co-ordinates. Examples considered include confined and unconfined aquifers, aquifers having a sloping base and time-variant behaviour. A study of an aquifer with a horizontal band of lower hydraulic conductivity shows that in this situation the groundwater-head approximation may not be acceptable.